There is a computer system having a configuration in which a computer is connected to a plurality of disk devices via a network. In this computer system, performance of access to data is improved by providing a cache.
For example, it is known, in a computer system in which a computer and a storage device is connected by a bus, to provide a cache in an input and output unit of the computer, to count a frequency of access to a disk device, and to cache data according to the frequency (Japanese Laid-Open Patent Publication No. 2001-134522).
Further, it is known, in a computer system in which a host computer and a shared memory are connected by a network, to provide a cache connected to other networks, to monitor an access state in a disk control device, and to provide an administrating person with such information that recommends shift of data or the like concerning a logical volume which is frequently accessed among disk devices (Japanese Laid-Open Patent Publication No. 2002-333956).